Many frequent flyers stand by the fact that if you keep yourself hydrated and get plenty of rest the effects of jet lag should go within a few days. However, there are some other ways to stop Jet Lags effects and there are remedies to stop you getting it all together.
London to Philadelphia jet lag information
Lets assume you left London at 9:00am. The flight takes approximately 6 hours 56 minutes so you would arrive in Philadelphia at 9:12am London time which is in fact 4:12am Philadelphia time.
Your body will be telling you that its 9:12am but actually its now 4:12am